KR101232590B1 - Method for preparing porphyrin xerogel thin film using porphyrin derivative used for preparing xerogel thin film - Google Patents

Abstract

The present invention relates to a porphyrin derivative for forming a zero gel thin film and a method for manufacturing a zero gel thin film using the same. More particularly, the present invention can be applied as a charge trap material or a semiconductor channel material by introducing a condensable substituent such as a hydroxyl group. The present invention relates to a porphyrin derivative for forming a zero gel thin film and a method for manufacturing a zero gel thin film which can be formed by a solution process such as spin coating or dip coating using the same.

Porphyrin derivatives, zero-gel thin films, memory devices, charge trapping materials, spin coating

Description

Method for preparing porphyrin xerogel thin film using porphyrin derivative used for preparing xerogel thin film}

1 is a thermogravimetric analysis (TGA) graph of porphyrin derivatives according to the present invention.

Figure 2 is a graph showing the thickness change of the porphyrin zero gel thin films prepared in Examples 1 and 2 of the present invention.

3 is a schematic cross-sectional view of the MOS transistor device manufactured in Example 3 of the present invention.

4 is a capacitance-voltage measurement graph of the test device manufactured in Example 3 of the present invention.

The present invention relates to a porphyrin derivative for forming a zero gel thin film and a method for manufacturing a zero gel thin film using the same. More particularly, the present invention can be applied as a charge trap material or a semiconductor channel material by introducing a condensable substituent such as a hydroxyl group. The present invention relates to a porphyrin derivative for forming a zero gel thin film and a method for manufacturing a zero gel thin film which can be formed by a solution process such as spin coating or dip coating using the same.

Recently, due to the remarkable development of the information and communication industry, the demand for various memory devices is rapidly increasing. In particular, memory devices required for portable terminals, various smart cards, electronic money, digital cameras, game memory, MP3 players, and the like are required for nonvolatile and large capacity characteristics.

Flash memory, which is widely used at present, is highly integrated and non-volatile like DRAM, which has excellent data integrity and low power consumption, and is particularly compact and lightweight, so that portable terminals, various smart cards, digital cameras, and MP3 players can be used. It has optimum characteristics as an external storage device of an electronic portable device such as the like.

Flash memory has a structure in which a memory cell, which is a basic element thereof, is sequentially stacked with a floating gate in which charge is stored in a gate of a transistor, that is, a floating gate in which data is stored, and a control gate controlling the same. Is common. Recently, in order to solve the problem of low retention of flash memory and to effectively reduce the vertical height, an oxide, nitride and oxide are sequentially laminated. Research into various types of memory cells, such as so-called SONOS memory devices, has been actively conducted.

In flash memory, information storage is exploited by the characteristic that the threshold voltage shifts as the charge tunneled to the floating gate is trapped. Since the information storage method in the conventional flash memory is complicated by the structure of the device and the top-down fabrication method, the cell size is reduced or the information is stored to increase the information storage density due to serious device deformation and multi-level blurring. It is difficult to continuously increase the level.

Recently, a technique for storing a plurality of bits of data in one memory cell to improve the density of a flash memory device, multi-bit, multi-level, or multi-state memory There is an active research on devices, and there is much interest in the semiconductor industry.

In the case of organic molecules capable of having various oxidation or reduction states, there are advantages in that discontinuous multiple levels are included in the molecule inherently, so that no additional device structure or process is required to realize the multi levels.

The present invention has been made on the background of the above-described prior art, and one object of the present invention is to provide a porphyrin derivative for forming a zero gel thin film which can be utilized as a channel material such as an electron trap material by introducing a condensable substituent by heat treatment. It is.

Another object of the present invention relates to a method for preparing a porphyrin zero gel thin film which can be prepared by a solution process such as spin coating or dip coating using the porphyrin derivative.

Another object of the present invention relates to an electronic device comprising a porphyrin zero gel thin film prepared by the above method as a charge trapping material.

One aspect of the present invention for achieving the above object relates to a porphyrin compound for forming a zero gel thin film represented by the following formula (1).

delete

[Formula 1]

In this formula,
M is selected from the group consisting of zinc (Zn), cobalt (Co), nickel (Ni), iron (Fe), magnesium (Mg), copper (Cu) and platinum (Pt),

X1, X2, X3 and X4 each independently represent a substituted or unsubstituted C1-C30 alkylene group, a substituted or unsubstituted C2-C30 alkenylene group, a substituted or unsubstituted C2-C30 alkynylene group, a substitution Or an unsubstituted C6-C30 arylene group, a substituted or unsubstituted C7-C30 arylalkylene group, a substituted or unsubstituted C1-C30 heteroalkylene group, a substituted or unsubstituted C4-C20 heteroarylene group, And a substituted or unsubstituted C4-C20 heteroarylalkylene group,

Y1, Y2, Y3 and Y4 each independently represent a hydroxyl group (-OH), a thiol group (-SH), a carboxyl group (-COOH), a thiocarboxyl group (-S- (C = O) -CH ₃ ), an acetic group (-O- (C = 0) -CH ₃ ) and acetoacetic group (-O- (C = O) -CH _2- (C = O) -CH ₃ ).

Another aspect of the present invention for achieving the above object is, iii) forming a coating film by applying a precursor solution comprising a porphyrin compound represented by the formula (1) and an organic solvent on a substrate; Ii) drying the coating film; And iii) relates to a method for producing a porphyrin zero gel thin film comprising the step of curing the coating film.

Another aspect of the present invention for achieving the above object relates to an electronic device comprising a porphyrin zero gel thin film produced by the method as a channel material layer.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

Porphyrin-based compounds are aromatic macrocycles consisting of four pyrrole units and four methine bridges around metal atoms, including 22 p-electrons, very stable at room temperature, and relatively low potential It has multiple cationic states accessible at. In addition, the charge retention time is characterized by the fact that the charge discharge is gradually occurred with 10 seconds or more, and the charge retention capacity is excellent to about 500fF / 5㎛ ² . The porphyrin compound according to the present invention is shown in the following formula (1). The porphyrin compound according to the present invention, by introducing a condensable substituent in the heat treatment process to the four methine bridges not only enables a solution process such as spin coating in the manufacture of a zero gel thin film, but also stores multi-level information in a memory device. The advantage is that it can be utilized as a charge trapping material.

[Formula 1]

In this formula,
M is selected from the group consisting of zinc (Zn), cobalt (Co), nickel (Ni), iron (Fe), magnesium (Mg), copper (Cu) and platinum (Pt),

X1, X2, X3 and X4 each independently represent a substituted or unsubstituted C1-C30 alkylene group, a substituted or unsubstituted C2-C30 alkenylene group, a substituted or unsubstituted C2-C30 alkynylene group, a substitution Or an unsubstituted C6-C30 arylene group, a substituted or unsubstituted C7-C30 arylalkylene group, a substituted or unsubstituted C1-C30 heteroalkylene group, a substituted or unsubstituted C4-C20 heteroarylene group, And a substituted or unsubstituted C4-C20 heteroarylalkylene group,

Y1, Y2, Y3 and Y4 each independently represent a hydroxyl group (-OH), a thiol group (-SH), a carboxyl group (-COOH), Thiocarboxyl group (-S- (C = O) -CH ₃ ), Acetic group (-O- (C = 0) -CH ₃ ) and Acetoacetic group (-O- (C = O) -CH2- (C = O) -CH ₃ ).

Preferred examples of the porphyrin derivatives according to the present invention include compounds of formula (2) wherein the central metal (M) is zinc (Zn) and four methine bridges are substituted with hydroxymethyl groups.

[Formula 2]

The principle that such a porphyrin derivative can be utilized as a charge trapping material of a memory is as follows. For example, when the zero gel thin film formed from the porphyrin derivative according to the present invention is formed on the semiconductor layer of the memory device, the number of free electrons liberated from the porphyrin compound may be controlled by controlling the voltage applied to the control gate. The multi-level is realized by adjusting the source-drain current I _DS according to the positive charge number of the porphyrin compound thus produced. For example, a state in which no charge is generated during a memory device reading process is represented by state "0", a case in which +1 positive charge is stored in porphyrin, and a state in which "+1" is stored in porphyrin. a can be defined as a state "2", as these three states ( "0", "1", "2") in the write (writing) process the information by applying a voltage of a voltage source according to, I _DS The value is changed so that three different states of the charge stored in the porphyrin compound can be read. Therefore, when the porphyrin derivative of the present invention is utilized as a charge trapping material, by storing multiple bits of information in a single memory cell, the information storage density can be effectively increased even in devices of the same space and the same density.

Another aspect of the present invention relates to a method for producing a porphyrin zero gel thin film using such a porphyrin derivative.

Method for producing a porphyrin zero gel thin film according to the present invention, iii) applying a precursor solution containing a porphyrin derivative represented by the formula (1) and an organic solvent on a substrate to form a coating film; Ii) drying the coating film; And iii) curing the coating film.

Specific examples of the porphyrin derivative used in the present invention include a compound represented by the following formula (2).

 [Formula 2]

Referring to the process of forming a zero gel thin film using a porphyrin derivative according to an embodiment of the present invention as shown in Scheme 1.

[Reaction Scheme 1]

이다.In the above scheme,

to be.

The precursor solution used to form the zero gel thin film of the present invention may be prepared as a sol solution in which sol particles are grown by adjusting temperature, a catalyst, a solvent, and the like, and are subjected to a drying step and a curing step in a wet gel state. Substituents such as hydroxy group (-OH) bonded to the porphyrin derivatives during the polymerization (condensation) between the porphyrin molecules as shown in Scheme 1 to form an intermolecular bond to form a three-dimensional network do. The precursor solution comprising a porphyrin derivative and an organic solvent according to the present invention enables a solution process such as spin coating, and since thermal decomposition is possible since decomposition does not occur at least 420 ° C., a thin film of porphyrin nanolayer having excellent thermal stability is obtained. Can be formed.

The precursor solution used in the present invention may be prepared by mixing two or more different kinds of porphyrin derivatives represented by the formula (1). The porphyrin derivative of formula 1 is preferably 0.1 to 30% by weight in the precursor solution.

The organic solvent used in the present invention is not particularly limited, preferably aliphatic hydrocarbon solvents such as hexane and heptane; Aromatic hydrocarbon solvents such as pyridine, quinoline, anisol, mesitylene and xylene; Ketone-based solvents such as methyl isobutyl ketone, 1-methyl-2-pyrrolidinone, cyclohexanone, and acetone ); Ether-based solvents such as tetrahydrofuran and isopropyl ether; Acetate-based solvents such as ethyl acetate, butyl acetate, and propylene glycol methyl ether acetate; Alcohol-based solvents such as isopropyl alcohol and butyl alcohol; Amide solvents such as dimethylacetamide and dimethylformamide; Silicon-based solvents; And one or more selected from the group consisting of a mixture of these solvents.

The precursor solution may further include a catalyst such as HCl / H ₂ O, H ₂ SO ₄ / H ₂ O, NaOH / H ₂ O, LiOH / H ₂ O, and the like as needed.

When the precursor solution is prepared in this way, the precursor solution is coated on the substrate to form a coating film. The substrate on which the coating film is formed in the present invention is not particularly limited as long as the object of the present invention is not impaired, and any substrate capable of withstanding thermal curing conditions, for example, a glass substrate, a silicon wafer, an ITO glass, and quartz ), A silica coated substrate, an alumina coated substrate, a plastic substrate and the like can be selected and used depending on the application.

In addition, a method of applying the precursor solution onto the substrate may include spin coating, dip coating, roll coating, screen coating, spray coating, and spin casting ( Coating methods such as spin casting, flow coating, screen printing, ink jet or drop casting can be used. The most preferred coating method in terms of convenience and uniformity is spin coating. When performing spin coating, the spin speed ranges from 100 to 10,000 rpm It is desirable to adjust within.

A coating film is formed on the substrate, and then the coating film is dried. The drying step is a process of wet gelation by evaporating the residual solvent, and packing between the porphyrin derivative molecules is caused by van der Waals attraction and dipole-dipole interaction. The drying step can be carried out simply by exposing to the ambient environment, applying a vacuum in the initial stages of the curing process, or by heating under a nitrogen atmosphere for 0.1 to 5 minutes at a temperature of 50 to 100 ° C.

The coating film goes through a drying step followed by a curing step. Curing step is a step of forming an intermolecular bond by the thermal decomposition and polymerization of the bonded substituent (Y), the coating film for 1 to 60 minutes at a temperature of 300 to 370 ℃, and a temperature of 380 to 420 ℃ It may be carried out by sequentially heat treatment for 1 to 60 minutes at, or may be cured by heat treatment gradually increasing the temperature from 300 ℃ to 420 ℃. At this time, the curing step is preferably carried out in a nitrogen atmosphere or vacuum. In the case of thermal curing in a vacuum state, the thermal decomposition of the porphyrin derivative itself can be prevented, so that a zero defect thin film can be produced, which is more preferable.

As can be seen from the capacitance and voltage measurement graph, the zero gel thin film manufactured by the method of the present invention generates hysteresis, which is utilized as a charge trapping material in a flash memory type nonvolatile memory device. The channel material layer may be constructed. In addition, since the porphyrin derivative itself has an exciton property, the zero gel thin film may be utilized as a semiconductor layer in electronic devices such as light emitting diodes, sensors, and solar cells.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the following Examples are for illustrative purposes only and are not intended to limit the present invention.

Preparation Example : Synthesis of Porphyrin Derivative (Zinc tetra- (p-hydroxybenzyl) -porphyrin)

5,10,15,20-tetrakis (4-methoxycarbonylphenyl) porphyrin [5,10,15,20-tetrakis (4-methoxycarbonylphenyl) porphyrin]

Methyl 4-formylbenzoate (1.477 g, 9.00 mmol), pyrrole (0.640 mL, 9.22 mmol) and NaCl (0.867 g, 14.84 mmol) were dissolved in CH ₂ Cl ₂ (1 L) and , BF ₃ · OEt ₂ (0.17 mL, 1.35 mmol) was added with stirring at room temperature. The solution was stirred for 1.5 hours, DDQ (1.69 g, 7.45 mmol) was added successively and then stirred for 12 hours. The mixture was washed with water and the organic solution was distilled off under reduced pressure. The residue was purified by column chromatography on silica to give porphyrin compound 1 (5,10,15,20-tetrakis (4-methoxycarbonylphenyl) porphyrin) (0.93 g, 49%).

¹ H NMR (300 MHz, CDCl ₃ ) δ -2.80 (s, 2H), 4.13 (s, 12H), 8.31 (d, J = 8.2 Hz, 8H), 8.46 (d, J = 8.2 Hz, 8H), 8.83 (s, 8 H); MALDI-TOF MS calcd for C ₅₂ H ₃₈ N ₄ O ₈ m / z 846.2690, found 846.2644

Zn (II) 5,10,15,20-tetrakis (4-methoxycarbonylphenyl) porphyrin (2) Zinc (II) 5,10,15,20-tetrakis (4-methoxycarbonylphenyl) porphyrin (2) ]

A solution of Zn (OAc) ₂ (1.1 g, 6.0 mmol) in methanol (10 mL) was added to the porphyrin compound (1) solution (1.0 g, 1.18 mmol) obtained above, and stirred for 1 hour. The mixture is then washed with water and the solvent is distilled off. The remaining solid was purified by column chromatography to obtain 1.07 g (quant.) Of porphyrin compound (2) [zinc (II) 5,10,15,20-tetrakis (4-methoxycarbonylphenyl) porphyrin].

¹ H NMR (300 MHz, DMSO- d ₆ ) δ 4.04 (s, 12H), 8.33 (d, J = 8.4 Hz, 8H), 8.39 (d, J = 8.4 Hz, 8H), 8.79 (s, 8H) ; MALDI-TOF MS calcd for C ₅₂ H ₃₆ N ₄ O ₈ Zn m / z 908.1825, found 908.2232

Zinc (II) 5,10,15,20-tetrakis (4-hydroxymethylphenyl) porphyrin [Zn (II) 5,10,15,20-tetrakis (4-hydroxymethylphenyl) porphyrin]

Lithium aluminum hydride solution (17.6 mL, 17.6 mmol) was added to the porphyrin compound (2) (1.00 g, 1.1 mmol) CH ₂ Cl ₂ / THF solution under nitrogen atmosphere. The mixture was stirred at 80 ° C for 20 h. The solution was diluted with THF, washed with water and then dried over anhydrous sodium sulfate. After the drying agent was filtered off, the organic solutions were combined and distilled under reduced pressure. The residue was purified by column chromatography to give a purple solid porphyrin derivative [Zinc (II) 5,10,15,20-tetrakis (4-hydroxymethylphenyl) porphyrin] (0.695 g, 79%).

¹ H NMR (300 MHz, DMSO- d ₆ ) δ 4.87 d, J = 5.7 Hz, 8H), 5.49 (t, J = 5.7 Hz, 4H), 7.73 (d, J = 8.0 Hz, 8H), 8.13 ( d, J = 8.0 Hz, 8H), 8.78 (s, 8H); ¹³ C NMR (100 MHz, CDCl ₃ ) δ 63.349, 120.607, 125.039, 131.892, 134.294, 141.480, 142.021, 149.693; UV-vis (THF) λ _max (ε) 424 (668900), 557 (21800), 595 (6200); MALDI-TOF MS calcd for C ₄₈ H ₃₆ N ₄ O ₄ Zn m / z 796.2028, found 796.3730

A thermogravimetric analysis (TGA) graph of the porphyrin derivative synthesized in the preparation example is shown in FIG. 1. Referring to Figure 1, it can be seen that the decomposition did not occur until the porphyrin derivative reaches a temperature of 420 ℃. Therefore, it can be seen that the porphyrin derivative according to the present invention is suitable for an annealing temperature of at least 420 ° C. for forming an oxide film having few defects.

Example  One : Zero gel  Manufacture of thin film

First, 0.06 g of the porphyrin compound obtained in the above preparation example and 0.94 g of tetrahydrofuran were mixed to prepare a precursor solution (6%) for preparing a zero gel thin film. The precursor solution was spin-coated on a 4 "silicon wafer for 20 seconds at 500 rpm and dried on a hot plate in nitrogen atmosphere for 1 minute at 70 ° C. The solvent was removed at 350 ° C. in a nitrogen atmosphere. Heat-treated for 30 minutes at, and then cured by heat treatment at 400 ℃ for 30 minutes to prepare a zero gel thin film.

Example  2 : Zero gel  Manufacture of thin film

In Example 1, a precursor solution (3%) was prepared using 1.94 g of pyridine as a solvent when preparing the precursor solution, and the dried coating film was heat-treated at 350 ° C. for 30 minutes in a nitrogen atmosphere, and then at 420 ° C. in a vacuum state. A zero gel thin film was prepared by performing the same process except that the mixture was cured by heat treatment for 1 hour.

The thickness change of the thin film according to the manufacturing steps of the zero gel thin films prepared in Examples 1 and 2 is shown in FIG. 2. Referring to FIG. 2, it can be seen that a zero gel thin film without pyrolysis may be formed even when the curing step is performed in a vacuum state.

Example  3 : Between gate insulating film Porphyrin Zero gel  Thin film MOS  Fabrication of Transistor Test Devices

3 is a schematic cross-sectional view of a MOS transistor test device according to Embodiment 3 of the present invention. As shown in Fig. 3, first, SiO ₂ was deposited to a thickness of 35 kW on the polycrystalline silicon substrate having a thickness of 100 kW as a semiconductor substrate using a thermal evaporation method as a gate insulating film. On top of that, the porphyrin derivative obtained in the preparation example was spin-coated by dissolving in a pyridine solvent at a concentration of 3%, and heat-treated at 400 ° C. for 1 hour in a vacuum to deposit a porphyrin zero gel thin film having a thickness of 1200 Pa. Subsequently, SiO ₂ was deposited on the zero-gel thin film to a thickness of 100 GPa using PECVD, and then Al was formed with a gate electrode of 0.5 mm in diameter to complete the MOS transistor test device.

In the MOS transistor test device manufactured according to Example 3, the capacitance was measured in the range of -40 to 40V, and the capacitance-voltage graph is shown in FIG. 4. The measurement equipment used a Precision LCR meter HP4284A (Agilent) and measured at a frequency of 1MHz.

Referring to FIG. 4, in the case of the MOS transistor including the zero gel thin film using the porphyrin derivative according to the present invention, a hysteresis phenomenon is indicated, which means that a charge trap occurs by the porphyrin zero gel thin film. As can be seen from the above results, the porphyrin derivative according to the present invention can be applied to a memory device using such a phenomenon.

Although the preferred embodiment has been described above as an example, the present invention can be variously modified within the scope not departing from the protection scope of the invention, it should be construed that such various modifications are included in the protection scope of the invention.

As described above, the porphyrin derivative according to the present invention can be utilized as a charge trapping material and a semiconductor channel material that can store multi-level information in a memory device, and can be used as a zero-gel solution through a room temperature solution process such as spin coating or dip coating. The thin film may be usefully applied to electronic devices such as memory, light emitting diodes, sensors, and solar cells.

Claims (16)

delete delete delete Iii) forming a coating film by applying a precursor solution containing a porphyrin derivative represented by the following Formula 1 and an organic solvent on a substrate, Ii) drying the coating film; Iii) a method of preparing a porphyrin zero gel thin film, which comprises curing the coating film: [Formula 1]

Where M is selected from the group consisting of zinc (Zn), cobalt (Co), nickel (Ni), iron (Fe), magnesium (Mg), copper (Cu) and platinum (Pt), X1, X2, X3 and X4 are each independently C1-C4 lower alkylene group, Y1, Y2, Y3 and Y4 are each independently a hydroxyl group (-OH). The method of claim 4, wherein the porphyrin derivative is a compound represented by the following formula (2):  [Formula 2]

The method of claim 4, wherein the precursor solution is prepared by mixing two or more different kinds of porphyrin derivatives represented by the formula (1). 5. The method of claim 4, wherein the porphyrin derivative of formula 1 is 0.1-30 wt% in the precursor solution. 6. The process of claim 4, wherein the organic solvent comprises an aliphatic hydrocarbon solvent comprising hexane and heptane; Aromatic hydrocarbon solvents including pyridine, quinoline, anisole, mesitylene and xylene; Ketone solvents including methyl isobutyl ketone, 1-methyl-2-pyrrolidinone, cyclohexanone and acetone; Ether solvents including tetrahydrofuran and isopropyl ether; Acetate-based solvents including ethyl acetate, butyl acetate and propylene glycol methyl ether acetate; Alcohol solvents including isopropyl alcohol and butyl alcohol; Amide solvents including dimethylacetamide and dimethylformamide; Silicone solvents; And at least one selected from the group consisting of a mixture of these solvents. The porphyrin zero gel of claim 4, wherein the precursor solution is applied using spin coating, dip coating, roll coating, screen coating, spray coating, spin casting, flow coating, screen printing, inkjet or drop casting. Method of manufacturing a thin film. 5. The method of claim 4, wherein the drying step is performed under a nitrogen atmosphere at a temperature of 50 to 100 ° C. for 0.1 to 5 minutes. 6. 5. The method of claim 4, wherein the curing step is performed sequentially for 1 to 60 minutes at a temperature of 300 to 370 ° C. and for 1 to 60 minutes at a temperature of 380 to 420 ° C. 6. . The method of claim 4, wherein the curing step is performed by gradually increasing the temperature from 300 ° C. to 420 ° C. 6. The method of claim 4, wherein the curing step is performed in a nitrogen atmosphere or a vacuum state. A porphyrin zero gel thin film prepared by the method according to claim 4. An electronic device comprising the porphyrin zero gel thin film of claim 14. The electronic device of claim 15, wherein the electronic device is selected from the group consisting of a memory, a light emitting diode, a sensor, and a solar cell.

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